scholarly journals A numerical study of vibration-induced instrument reading capability degradation in helicopter pilots

2021 ◽  
Author(s):  
Aykut Tamer ◽  
Andrea Zanoni ◽  
Alessandro Cocco ◽  
Pierangelo Masarati
Keyword(s):  
Reading Ability ◽  
Numerical Study ◽  
Coupled Model ◽  
Instrument Panel ◽  
Human Machine Interaction ◽  
Multibody Model ◽  
Instrument Reading ◽  
Design Changes ◽  
Helicopter Pilots ◽  
Core Elements

AbstractRotorcraft suffer from relatively high vibratory levels, due to exposure to significant vibratory load levels originating from rotors. As a result, pilots are typically exposed to vibrations, which have non-negligible consequences. Among those, one important issue is the degradation of instrument reading, which is a result of complex human-machine interaction. Both involuntary acceleration of the eyes as a result of biodynamics and vibration of the instrument panel contribute to a likely reduction in instrument reading capability, affecting flight safety. Therefore, being able to estimate the expected level of degradation in visual performance may give substantial benefits during vehicle design, allowing to make necessary adjustments while there is room for design changes or when retrofitting an existing aircraft to ensure the modifications do not adversely affect visual acuity and instrument reading ability. For this purpose, simulation is a very valuable tool as a proper model helps to understand the aircraft characteristics before conducting flight tests. This work presents the assessment of vibration-induced visual degradation of helicopter pilots under vibration exposure using a modular analysis environment. Core elements of the suggested analysis framework are an aeroelastic model of the helicopter, a model of the seat-cushion subsystem, a detailed multibody model of the human biodynamics, and a simplified model of ocular dynamics. These elements are combined into a comprehensive, fully coupled model. The contribution of each element to instrument reading degradation is examined, after defining an appropriate figure of merit that includes both eye and instrument panel vibration, in application to a numerical model representative of a medium-weight helicopter.

Visual Performance Evaluation of Helicopter Pilots in Vibrating Cockpit

2019 ◽  
Author(s):  
Aykut Tamer ◽  
Andrea Zanoni ◽  
Alessandro Cocco ◽  
Pierangelo Masarati
Keyword(s):  
Reading Performance ◽  
Visual Performance ◽  
Instrument Panel ◽  
Multibody Model ◽  
Design Changes ◽  
Seat Cushion ◽  
Vibratory Load ◽  
Helicopter Pilots ◽  
Core Elements ◽  
Modular Analysis

Abstract Rotorcraft are known to suffer from relatively high levels of vibration as compared to their fixed-wing counterpart, due to exposure to significant vibratory load levels. Pilots usually operate in a vibrating cockpit, and hence can suffer from degradation of their instrument reading performance. Therefore, the expected level of degradation in visual performance should be estimated when there is room for design changes. The present work demonstrates the evaluation of visual vibration degradation of helicopter pilots using a modular analysis environment. Core elements are an aeroelastic helicopter model, a seat-cushion model, a detailed human biodynamics multibody model, and a simplified model of ocular dynamics, which are assembled into an overall model. The contribution of each component is examined using a figure of merit that includes both eye and instrument panel vibration.

scholarly journals Numerical study on deployment of subsea template using coupled and uncoupled model

2021 ◽  
Vol 1201 (1) ◽  
pp. 012020
Author(s):  
N O Hauge ◽  
L Li
Keyword(s):  
Time Domain ◽  
Numerical Study ◽  
Coupled Model ◽  
Simulation Software ◽  
Time Domain Simulation ◽  
Coupled Models ◽  
Sea State ◽  
The Time Domain ◽  
Vessel Motion ◽  
Simulation Time

Abstract This study compares deployment of a subsea template simulated as a coupled model and as an uncoupled model in the time domain simulation software Orcaflex. Defining vessel motion as prescribed simplifies the model and will therefore also decrease the simulation time. Models with predefined vessel motions are called uncoupled models. Vessel motion in a coupled model is a continuously calculated reaction to the forces acting on the vessel. Some software might struggle to run coupled models. The deployment simulations are narrowed down to focus on the incident where the template crosses the splash zone when lifted with an offshore construction vessel. Noticeable differences between the allowable sea state results are observed from the two different simulation methods. Running the time domain simulation as an uncoupled model gives lower allowable sea states than the results from the coupled time domain simulation model.

Rotorcraft Pilot Impedance From Inverse Dynamics-Based Biomechanical Model

2012 ◽  
Author(s):  
Andrea Zanoni ◽  
Giuseppe Quaranta ◽  
Pierangelo Masarati
Keyword(s):  
Inverse Dynamics ◽  
Biomechanical Model ◽  
Biomechanical Properties ◽  
Activation Patterns ◽  
Joint Torques ◽  
Multibody Model ◽  
Equivalent Impedance ◽  
Helicopter Pilots ◽  
Machine Interface ◽  
Muscular Activation

The involuntary interaction of the pilot with a vehicle is often an undesired consequence of the biomechanical properties of the human body and its relation with the layout of the man-machine interface. This work discusses how muscular activation patterns affect the variability of the equivalent impedance of helicopter pilots. A multibody model is used to compute the joint torques associated to a prescribed pilot task, which are then transformed into corresponding ‘optimal’ muscular activation patterns. Equivalent pilot impedance is obtained by consistently linearizing the constitutive model of the muscles about the reference activation. The effect on equivalent impedance of non-optimal activation, resulting from the addition of Torque-Less Activation Modes to the optimal activation, is evaluated and discussed.

Numerical study of coastal hydrodynamics using a coupled model for Hudhud cyclone in the Bay of Bengal

2016 ◽  
Vol 183 ◽  
pp. 13-27 ◽  
Author(s):  
P.L.N. Murty ◽  
Prasad K. Bhaskaran ◽  
R. Gayathri ◽  
Bishnupriya Sahoo ◽  
T. Srinivasa Kumar ◽  
...  
Keyword(s):  
Bay Of Bengal ◽  
Numerical Study ◽  
Coupled Model ◽  
Coastal Hydrodynamics

scholarly journals Numerical Study of Wave- and Current-Induced Oscillatory Seabed Response near a Fully Buried Subsea Pipeline

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Lunliang Duan ◽  
Meiling Fan ◽  
Duoyin Wang ◽  
Caixia Meng ◽  
Lei Xing
Keyword(s):  
Laboratory Experiments ◽  
Present Model ◽  
Numerical Study ◽  
Coupled Model ◽  
Navier Stokes ◽  
Comsol Multiphysics ◽  
Buried Pipeline ◽  
Subsea Pipeline ◽  
Current Interaction ◽  
Fluid Characteristics

To investigate the wave- and current-induced seabed response near a fully buried subsea pipeline, a two-dimensional coupled model for fluid-seabed-pipeline interaction (FSPI-2D) is developed within the framework of COMSOL multiphysics. Different from previous studies, both the wave-current interaction and the nonlinear pipeline-soil contacts are considered in the present model. In this paper, Biot’s consolidation mode is used to govern the fluid-induced seabed response, and combined Reynolds averaged Navier–Stokes (RANS) equation with the k-ε turbulence model is employed to simulate the fluid propagation. Meanwhile, the pipeline is treated as a linear elasticity. Firstly, the effectiveness of the new model is verified by laboratory experiments from previous reports. Then, the numerical model is employed to examine the effects of nonlinear pipeline-seabed contacts and fluid characteristics on the seabed response around the structure. Finally, the momentary liquefaction near the fully buried pipeline is studied based on the 2D coupled model.

scholarly journals A Numerical and Experimental Investigation of the Impact of Mixed Flow Turbine Inlet Cone Angle and Inlet Blade Angle

2018 ◽  
Author(s):  
Thomas Leonard ◽  
Stephen Spence ◽  
Dietmar Filsinger ◽  
Andre Starke
Keyword(s):  
Numerical Study ◽  
Velocity Ratio ◽  
Cone Angle ◽  
Blade Angle ◽  
Mixed Flow ◽  
Automotive Engine ◽  
Transient Behaviour ◽  
Design Changes ◽  
Wide Range ◽  
The Impact

Mixed flow turbines offer potential benefits for turbocharged engines when considering off-design performance and engine transient behaviour. Although the performance and use of mixed flow turbines is described in the literature, little is published on the combined impact of the cone angle and the inlet blade angle, which are the defining features of such turbines. Numerical simulations were completed using a CFD model that was validated against experimental measurements for a baseline geometry. The mechanical impact of the design changes was also analysed. Based on the results of the numerical study, two rotors of different blade angle and cone angle were selected and manufactured. These rotors were tested using the QUB low temperature turbine test rig, which allowed for accurate and wide range mapping of the turbine performance to low values of velocity ratio. The performance results from these additional rotors were used to further validate the numerical findings. The numerical model was used to understand the underlying physical reasons for the measured performance differences through detailed consideration of the flow field at rotor inlet, and to document how the loss mechanisms and secondary flow structures developed with varying rotor inlet geometry. It was observed that large inlet blade cone angles resulted in strong separation and flow blockage near the hub at off-design conditions, which greatly reduced efficiency. However, the significant rotor inertia benefits achieved with the large blade cone angles were shown to compensate for the efficiency penalties and could be expected to deliver improved transient performance in downsized automotive engine applications.

scholarly journals Numerical Study on Thermal Environment in Mine Gob Under Coal Oxidation Condition

2013 ◽  
Vol 20 (3) ◽  
pp. 567-578 ◽  
Author(s):  
Yanming Wang ◽  
Guoqing Shi ◽  
Deming Wang
Keyword(s):  
Numerical Model ◽  
Spontaneous Combustion ◽  
Thermal Environment ◽  
Numerical Study ◽  
Coupled Model ◽  
Seepage Flow ◽  
Underground Mines ◽  
Oxidation Condition ◽  
Reaction Heat ◽  
Residual Coal

Abstract The most feared of hazards in underground mines are those of fires and explosions. This study focuses on the temperature-rising process of residual coal under spontaneous combustion condition in coal mine gob. A numerical model has been established considering the chemical reaction, heat transfer and components seepage flow. The temperature distributions and maximum values for different positrons at various times have been calculated by using the coupled model. An experimental model has been also developed for model calibration. The validation indicates the numerical model is accurate and suitable for solving the temperature-rising problem in coalmines. The simulation results show that high temperature zone appears at the air intake roadway side in the gob and enlarging the ventilation flux increases the risk of self-ignition of coal. The research results can be used to predict the temperature-rising of coal spontaneous combustion and coal resources prevention.

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